Another possible reason it might have rusted is if somebody put it in the dishwasher. Black carbon steel will do this, and I think a dishwasher will make it rust much more quickly than just leaving water in it.

Apparently, heating Teflon to 400 degrees will release gasses that kill birds. I really wouldn’t trust it not to have adverse health effects on humans, as well. And if you’re careless, it’s fairly easy to heat Teflon to this high a temperature on a stovetop. Be careful!

Aluminum is generally considered safe to eat; it’s the Teflon which can be poisonous if overheated.

Doesn't honey contain some anti-bacterial compounds, making it an even better preservative than sugar?

There are a number of oat products that say gluten free on them, at least int he U.S. If they don't say gluten free, don't eat them — in this case they are very likely to trigger your medical condition.

I can testify from experience that maple syrup can be attacked by more than one type of mold. I am fairly sure that if it's the usual kind of mold, then this advice (which can be found in multiple places on the internet) is fine. But if it's a different kind, I would just throw the syrup out (although the few drops I tasted before I noticed didn't seem to hurt me).

We store maple syrup on the shelf for months, and it only very rarely gets moldy.

The link says that the freezer is best to keep it for a "very long time". Since it keeps for well over a year in the refrigerator, if you use it reasonably often, there doesn't seem to be any need to freeze it.

I assume you mean salmonella dies at 70 or 75 degree C, and not 705 degree C (which is hot enough to melt aluminum).